It is well known to utilize colored yarns within textile materials to impart desired aesthetic characteristics to the textile material. Color is generally imparted to yarns by use of bulk dyeing practices in which a single color is applied to bundles of yarn immersed within a dye bath. Typical dyes as are known to those of skill in the art include disperse dyes, acid dyes and basic dyes. It is also known to heat set yarns by applying a tensioning force to the yarn under elevated temperature conditions. Such heat setting is typically used to impart an enhanced degree of uniformity to the yarn. As will be appreciated, when a yarn treated in accordance with prior practices is subjected to a bulk dyeing operation, the dyed yarn is typically of a substantially uniform solid color. Moreover, such yarns tend to behave in a substantially uniform manner when subjected to post-dyeing heat treatment.
In order to provide variation in color along the length of a yarn it is known to utilize so-called “space-dyed” yarns within pile-forming textile materials such as carpeting to provide a random or pseudo-random pattern within the material. One such carpeting material is illustrated and described in U.S. Pat. No. 5,413,832 to Willey the contents of which are incorporated by reference herein.
Several methods are known for space dyeing of yarns so as to impart segments of various colors along the length of such yarns. One such known method is the so-called “knit-deknit” method in which yarns are knit into a construction across which bands of color are introduced. The knit construction is thereafter unraveled so as to yield the lengths of yarn with substantially random coloration patterns disposed along their length. While useful, the “knit-deknit” process may be difficult to control and may be unduly time consuming and complex to enable efficient and cost effective manufacture of large quantities of material.
In order to address the deficiencies of the “knit-deknit” process, several batch-type and continuous processes have been advocated. Among the batch-type processes (in which a predetermined quantity of yarn is treated at one time), it is known to inject yarn packages with a number of different colored dyes to yield a space-dyed product. However, such batch process may be relatively costly and require more product handling than is desired.
As an alternative to the batch-type processes, several types of continuous space-dyeing processes (in which moving yarns are individually or collectively treated) are also known. One such continuous process is illustrated and described in U.S. Pat. No. 5,594,968 to Haselwander et al. the teachings of which are incorporated by reference herein. In this process yarns are intermittently pressed against dye applicator rolls to impart segments of dye to the yarns in a predetermined order. The yarn is held against the dye applicator rolls by a pattern roll supporting deflecting rods or paddles arranged in spaced relation at the surface of the pattern roll up stream of the dye applicator roll so as to provide a defined period of contact between the yarn and the dye applicator roll as the deflecting elements are pressed against the yarn at locations adjacent to the dye applicator rolls.
U.S. Pat. Nos. 5,491,858 and 5,557,953 to Massotte et al. (incorporated by reference) disclose equipment and procedures for applying dye segments to yarns using spinning disk elements having spaced openings which permit passage of dye droplets towards the yarns when the disk openings and yarns are in opposing relation to one another.
Another continuous process is illustrated and disclosed in U.S. Pat. No. 6,019,799 to Brown et al. the teachings of which are incorporated by reference herein. The process disclosed therein utilizes a substantially direct application of a spray pattern of dye liquor droplets towards a yarn sheet. The dye stream is cycled on and off to apply a desired patterning effect.
In view of the above, the prior art has addressed the desire for color variability along the yarn length by selective dye application at discrete yarn segments. While such practices may provide desirable aesthetic results, they also require a relatively high degree of complexity related to the controlled selective dye application. In particular, multiple dye delivery systems are required in combination with precision application equipment.